1. Field of the Invention
Frost sensitive agricultural plants are damaged when ice formation occurs within their tissues. Ice formation within the tissues causes a mechanical disruption of the cells giving rise to the symptoms known as frost injury. Most frost sensitive agricultural plants have no mechanism to tolerate the formation of ice within their tissues; whenever ice formation occurs within these tissues, frost injury results. Thus, these plant species have no mechanism for frost tolerance. However, it has been shown that the water within the plant tissues of these species has the innate ability to supercool, that is, to remain in a liquid state at temperatures below 0.degree. C. Certain species of bacteria have the property of ice nucleation so that their presence on the surface of the plants limits the ability of the water to supercool. Pseudomonas syringae, Erwinia herbicola or certain strains of Pseudomonas fluorescens, catalyze ice formation limiting supercooling to less than 1.degree. C.
It would therefore be desirable to develop economic and efficient means for preventing the ice nucleation caused by these microorganisms without harming the plant host and maintaining the protection during the period when the plant is subject to frost injury.
2. Description of the Prior Art
A paper was presented by Lindow, S. E., entitled, "Frost Damage To Pear Reduced By Antagonistic Bacteria, Bactericides and Ice Nucleation Inhibitors", Am. Phytopath Soc. Annual Meeting, Aug. 23-28, 1980. U.S. Pat. Nos. 4,045,910 and 4,161,084 describe the use of ice nucleating deficient microorganisms to inhibit frost injury.